Fuse for vacuum bulbs



May 6 1924,H 1,493,148

M, B. COHEN FUSE FOR VACUUM BULBS Filed July 23 1920 Fgl.

Im/enToT. Mongomeryohen Anya.

Patented ,May 6, 1924.l

UNITED STATES MONTGOMERY B. COHEN, OF BOSTON, MASSACHUSETTS.

FUSE FOR VACUUM BULBS.

Application filed July 2S, 1920. Serial No. 398,446.

To all whom t ma concern.'

Be it known t at I, MONTGOMERY B. COHEN, a citizen of the United States,and

resident of` Boston, county of Suffolk, State A of Massachusetts, haveinvented an Improvement in Fuses for Vacuum Bulbs, of which thefollowing description, in connection with the accompanying drawing, is aspecification, like characters on the drawing representing like parts.

This 'invention relates to vacuum bulbs and especially to those whichare used in wireless work, and the object of the invention is to providea novel means for rol5 tecting the bulb from the destructive e ects ofexcessive current.

In accordance with my invention I provide a protecting device which isconstructed to be interposed between the terminals of the bulb and theterminals of the socket in' which the bulb is placed, the device beingpreferably of a nature to be detachably applied to the terminals of thebulb.

In the preferred embodiment of ,my invention this protective deviceassumes the form of a fuse which will blow'when the current becomesexcessive thus breaking the circuit and protecting the bulb.

The fuse element embodying the inven- 80 tion is constructed so that itcan be applied to the filament terminals of the vacuum bulb withoutinterfering in anyway with the lacing the bulb into its socket orremovlng it therefrom. When the fuse is in place 85 the electricalconnections between'the bulb terminal, to which it is 'ap lied, and thecorresponding socket termina `is completed through the fuse and,therefore, if at any time the current should become excessive .the fusewill burn out before the filament is destroyed thus protecting thelatter.

In order to give an understanding of my invention I have illustrated inthe drawings a selected embodiment thereof which F ig. 3 is aperspective .view of the fuse element separated from the bulb terminal.

- Fig. 4 is a section on` the line 4-4 Fig. 2. In the drawings lindicates a Vacuum bulb of unusual construction, it havingtlie neckportion 2 adapted to be inserted intoa socket or holder 8 and alsohaving the four terminals 5, 6, 7 and 8 at the end of the neck 2, theseterminals being in the formy Vof proj ecting pins. The terminal 5connects to the grid element 9 within the bulb; the terminal 8' connectsto the plate element l0; and, the,

two terminals 6 and 7 are the terminals for the filament.

The bulb with-its filament, grid and plate may have any suitable orusual construction and does not form any part of my present invention. ii

I The socket or holder 3 is provided with four contactsor terminals 12which are Situated -to engage the ends ofthe bulb terminals 5, 6,7 and 8when thelatter is inserted into the socket, all as usual in devices ofthis nature. The parts thus far described are, or may be, all as usualin vacuum bulbs of this type'and form no part of my present invention.In using vacuum bulbs of this type it some -times happens that anexcessive current will arise which is s ufcient to burn out or destroythe filament 11 and when this happens the bulb is rendered unfit forfurther use and must be discarded. These, bulbs are more or lessexpensive to manufacture and it is of some importance, therefore, toprotect the filament from being burnedn out by an excessive current. Asstated above the present invention has this for its object and the saidobject is accomplished by the use of a fuse element, indicated generallyat 13, and of a. shape to fit over one of the` filament terminals and toform the contact between said filament terminalr andthe correspondingsocket contact 12.

` A fuse element embodying my `invention can be readily slipped ontoeither of the filament vterminals and when in place does not interferein any way with the placing of the bulb into the socket or its removaltherefrom. The fuse element is preferablycupshaped and is Lprovided witha sleeve-like contact member which fits the filament terminal, anothercontact member at its end Awhich is insulated from the first contactmember and which engages the contact 12 of the socket, and `a fusibleconnection between these two contact members.

lin theembodiment of the invention herein illustrated 14 indicates asleeve-like contact which is of a size to fit over the filament terminal7 and which is enclosed within a cylindrical body member 15 ofinsulating material. The outer end of this body member 15 -is preferablyclosed as shown at 16. @n'the end of the fuse element is a plate 17which forms the other contact thereof that is adapted to engage thesocket contact 12. This plate 17 is preferably formed as art of acupshaped member which can be orced over the end of the fuse and isretained in position thereon in any suitable way. The contacts 17 and 14are thus'insulated from eachother by the insulating body member 15, 16.18 indicates a fuse wire which connects the contacts 14 and 17. Thisfuse wire 18 may have any suitable locationnin the fuse, but ll find itconvenient to place it on the exterior of the body 15 and extendinglongitudinally thereof, one end of the wire being connected to thecontact 17 at 19 and the other end being connected to a Hanged portion20 of the contact 14 as shown at 21. lf desired a protecting sheath 22of glass, or any other insulating material,

may be placed around the body 15 thereby enclosing and protecting thefuse wire 18 d where this protecting sheath 22 is employed the capshaped contact 17 may be constructed to embrace the lower end of saidprotecting sheath.

The fuse 'thus made up constitutes a cuplike element which can beslipped over either of the lament terminals and will be held thereon byfrictional en agement therewith. When the fuse is plac i on the terminal7 the Abulb 1 may be inserted into the socket 3 and when thls is donethe contact element 17 of the fuse will be brought into engagementwiththe appropriate contact 12 of the socket and a properA electricalconnection between the lament terminal and the contact 12 will beadorded through the fuse. The presence of the fuse does not in any wayinterfere with the ordinary use of the bulb, but if vduring its use anexcessive current should arise which would be likely to injure thefilament 11 the fuse wire 1,8 will melt thus breaking the circuit to thefilament and preventing the latter from injury. When this happlens itwill simply be necessary to Jremove t e bulb and re ace the burned-outfuse by a fresh fuse, w en the bulb will be ready for use again.

From the above it will be seen that the fuse herein described can beapplied to anyl of the standard vacuum bulbs now incommon use withoutnecessitating any change .2in the bulb or in the sockets that are used.ln its broad aspect the fuseA constitutes if for protecting the bulb inthat it will incarne open the circuit when the current becomesexcessive.

My invention therefore in its broad sense is a protecting device whichis adaptedl to be applied'to one or moreof the terminals bulb having aterminal in the form of aD projection, said fuse element having a 'shapeto lit over the bulb terminal and provided with two contacts, oneengaging the bulbV terminal and the other adapted to engage the terminalof the socket into which the bulb is placed and a fuse wireconnectingsaid contacts.

2. rllhe combination with a vacuum bulb having terminals, of a socket toreceive said bulb and provided with contacts for the teinals, of a fuseelement detachably applied to one of the bulb terminals and constructedto engage the corresponding socket contact.

3. The combination with a vacuum bulb havin@ terminals, .in the form ofprojections extending therefrom, of a socket to receive said bulb dprovided with contacts to enga e said terminals and a fuse element detacably applied to one of the bulb terminals and constructed to engage thecorrespong socket contact.l

4. The combination with a vacuum bulb having terminals in the form ofprojections extendin therefrom, of a socket to receive said bul andprovided with contacts to enga -said terminals and 'a fuse element tteu!over one of the bulb terminals and having a contact adapted to engagethe corresponding socket contact.

5. The combination with a vacuum bulb having terminals in the form ofprojections extending therefrom, of a socket to receive said bulb andprovided with contacts to lll@ engage said terminals and a cup-shapedfuse element fitted over one of the bulb terminals and hafving at itsend a contact to engage the corresponding. socket contact. c

6. A fuse for use with terminals of electric bulbs, said fuse comprisinga sleevelike contact to fit over the bulb terminal,

abody of insulating material enclosing said ian l nal may be insertedand having a contact to engage said terminal, a second contact situatedto engage the socket terminal when a bulb having the fuse applied to itsterminal is placed in the socket, and a fuse wire y connecting thecontacts of the fuse element.

SUA hollow fuse element constructed to slip over a projecting terminalof an electric bulb, said element having two contacts, one of which isadapted to engage the projecting terminal when the element is placedthereover, and the other of which is situated at the end of the elementand is vadapted to engage the socket terminal when the bulb with thefuse element thereon is placed in the socket, and a fusible memberconnecting said contacts.

9. A protecting device for use with terminals of electric bulbs, saiddevice having a shape to fit over the bulb terminal and provided withtwo contacts, one engaging the bulb terminal and the other adapted toengage the terminal of the socket into which 10. The combination with avacuum bulb having terminals, of a socket to receive said bulb andprovided with contacts to engage the terminals of the bulb, said bulbbeing removably carried by the socket, and a fuse element'separable fromboth the socket and bulb and interposed between one terminal and thebulb of the corresponding contact of the socket.

ll. The combination with a vacuum bulb having terminals, of a holder toreceive said bulb and provided with contacts to engage said terminals,said bulb being separable from the holder, and a protective deviceseparable from both the bulb and holder and interposed between a bulbterminal and the correspond-ing holder contact.

In testimony whereof, I have signed my name to this specification.

MONTGOMERY B. COHEN. t

